Controlling and delivering gases in a plasma arc torch and related systems and methods

ABSTRACT

In some aspects, torch receptacles for coupling a plasma arc torch to a torch lead can include: a body having a first end to connect to the torch lead and a second end to connect to a torch body; a set of ports within the first end to fluidly connect to a set of fluid conduits within the torch lead; and a multiway valve within the body and fluidly connected to the set of ports and to a torch gas conduit formed in the second end, the multiway valve being configured to: i) manipulate a flow of fluids between the first end and the second end to select from primary gases entering the set of ports, ii) deliver a selected primary gas to the torch body through the torch gas conduit, and iii) fluidly connect the torch gas conduit to a gas supply manifold of the plasma cutting system.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/287,694, filed Oct. 6, 2016 and entitled “Controlling PlasmaArc Torches and Related Systems and Methods,” which claims the benefitof U.S. Provisional Patent Application Ser. No. 62/237,780, filed Oct.6, 2015 and entitled “Controlling Plasma Arc Torches and Related Systemsand Methods,” the contents of both of which are hereby incorporatedherein by reference in their entirety. This application also claims thebenefit of U.S. Provisional Patent Application Ser. No. 62/315,331 filedMar. 30, 2016, entitled “Gas Switching and Venting Proximate a PlasmaArc Torch,” the contents of which are hereby incorporated herein byreference in their entirety.

TECHNICAL FIELD

This disclosure relates generally to plasma arc torch systems and morespecifically to controlling and delivering gases to and within a plasmaarc torch and related systems and methods.

BACKGROUND

Thermal processing torches, such as plasma arc torches, are widely usedin the heating, cutting, gouging, and marking of materials. A plasma arctorch generally includes an electrode, a nozzle having a central exitorifice mounted within a torch body, electrical connections, passagesfor cooling, and passages for arc control fluids (e.g., plasma gas). Aswirl ring can be used to control fluid flow patterns in the plasmachamber formed between the electrode and the nozzle. In some torches, aretaining cap can be used to maintain the nozzle and/or swirl ring inthe torch body. In operation, a plasma arc torch produces a plasma arc,which is a constricted jet of an ionized gas with high temperature andsufficient momentum to assist with removal of molten metal. Power usedto operate plasma arc torches can be controlled by a power supplyassembly of a plasma operating system. The power supply and/or meteringconsole, which is often located distant relative to the torch (e.g.,several meters), can include a plurality of electronic componentsconfigured to control and supply an operational current to the plasmaarc torch, the gas flows provided to the plasma arc torch, and, in somecases, motion of the plasma arc torch. This distance between the torchand the power supply/metering console can vary system to system andinstallation to installation.

In plasma arc cutting systems, transient state electrode life, cutquality and consistency, and overall operations can be affected by or isdependent upon ramp times (e.g., the rate at which plasma current and/orplasma gas rises and drops during start-up and shut down), which can beselected during process parameter development for a given system. Theseprocess parameters (i.e., waveforms) typically reside in the powersupply (often many meters from the actual torch tip) and are independentof the system configuration being used. Some systems are configured toimplement certain gas during transition, start up, or shut down profilesand gas characteristics based on the desired characteristics of the arcduring use. For example, some systems can provide desirable gas flow orcurrent profile combinations for shut down.

SUMMARY

In some aspects, torch receptacles for coupling a plasma arc torch to atorch lead of a plasma cutting system and for upstream venting the torchlead, and in some cases the plasma arc torch, through the plasma cuttingsystem can include: a body having a first end shaped to connect to thetorch lead and a second end shaped to connect to a torch body of theplasma arc torch; a set of ports disposed within the first end of thebody and configured to fluidly connect to a set of fluid conduitsdisposed within the torch lead; and a multiway valve disposed within thebody and fluidly connected to the set of ports and to a torch gasconduit formed in the second end of the body, the multiway valve beingconfigured to: i) manipulate a flow of fluids between the first end andthe second end of the body to select from primary gases entering the setof ports, ii) deliver a selected primary gas to the torch body throughthe torch gas conduit, and iii) fluidly connect the torch gas conduit toa gas supply manifold of the plasma cutting system to permit venting ofthe torch gas conduit through the gas supply manifold.

Embodiments can include one or more of the following features.

The body can be formed of a substantially insulative material. The bodycan have a length of less than about 1 foot between the first end andthe second end. The body can define a set of fluid flow paths disposedsubstantially within the body to fluidly couple the multiway valve tothe fluid conduits within the torch lead.

The multiway valve can be a 3-way valve fluidly coupled to a firstconduit of the set of fluid conduits, a second conduit of the set offluid conduits, and the torch gas conduit and is configured to selectgas from either the first conduit or the second conduit and permitdelivery of the selected gas to the torch body via the torch gasconduit. The multiway valve can be located less than 12 inches from aplasma plenum of the plasma arc torch. The multiway valve can beconfigured to switch a supply of gas provided to the torch body via thetorch gas conduit between gases entering the set of ports.

The set of ports can include a first plasma gas port and a second plasmagas port, where the first plasma gas port is configured to receive aplasma pre-flow gas and the second plasma gas port is configured toreceive a plasma cut flow gas. The set of ports can include a shield gasport fluidly connected to a shield gas conduit formed between the firstend of the body and the second end of the body. The torch gas conduitcan have a volume of less than about 0.3 cubic inches. In some cases,the torch gas conduit has a volume of less than about 0.2 cubic inches.The torch lead can fluidly couple at least one of the set of conduits tovented atmospheric pressure. In some examples, an excess of plasma gasblocked from entering the torch gas conduit by the multiway valve isvented upstream through the torch lead.

In some aspects, plasma arc torch systems for back-venting plasma gasupstream through a plasma torch lead line can include: a plasma torchpower supply having: a set of gas supplies comprising a first plasma gasand a second plasma gas, a torch lead manifold to fluidly connect theset of gas supplies to the plasma torch lead line, and a vent valve tovent the first plasma gas to atmospheric pressure; a plasma torch leadline configured to couple to the torch lead manifold, the plasma torchlead line defining a set of fluid passages to convey the first plasmagas and the second plasma gas from the plasma torch power supply; and atorch receptacle for coupling a plasma arc torch to the plasma torchpower supply, the torch receptacle having a body having a first end tocouple to the plasma torch lead line and a second end shaped to connectto a torch body of the plasma arc torch, a set of ports defined withinthe first end of the body and configured to fluidly connect to the setof fluid passages of the plasma torch lead line, and a 3-way multiwayvalve disposed within the body and fluidly connected to the set ofports, to be fluidly coupled to a first passage of the set of fluidpassages in the plasma torch lead line and to a second passage of theset of fluid passages in the plasma torch lead line, and to a torch gasconduit formed in the second end of the body having a volume of lessthan about 0.3 cubic inches, the 3-way multiway valve being configuredto: i) manipulate a flow of fluids between the first end and the secondend of the body to select from primary gases entering the set of ports,ii) deliver a selected primary gas from either the first passage or thesecond passage to the torch body through the torch gas conduit, and iii)fluidly connect the torch gas conduit to a torch lead manifold of theplasma torch power supply to permit venting of the torch gas conduitthrough the torch lead manifold to atmospheric pressure.

In some aspects, methods of operating a plasma cutting system byselecting between a set of plasma gases in a torch receptacle coupling aplasma arc torch to a torch lead of the plasma cutting system, the torchreceptacle having a valve configured to manipulate a flow of fluids tothe plasma arc torch between the gases of the set of plasma gases, caninclude: supplying a pre-flow plasma gas through a first conduit of thetorch lead coupled to the torch receptacle, the pre-flow plasma gastraveling to the plasma arc torch through the valve; igniting a plasmaarc within the plasma arc torch in the presence of the pre-flow plasmagas; selecting a cut plasma gas by activating the valve to: i) limitfurther flow of the pre-flow plasma gas downstream to the plasma arctorch, and ii) permit flow of the cut plasma gas from a second conduitof the torch lead to the plasma arc torch through the valve; venting thefirst conduit of the torch lead to atmospheric pressure at a manifoldupstream of the plasma arc torch to release the pre-flow plasma gas fromthe torch lead; and performing a plasma cutting operation using the cutplasma gas.

Embodiments can include one or more of the following features.

The methods can further include activating the valve to: i) limitfurther flow of the cut plasma gas downstream to the plasma arc torchfrom the second conduit, and ii) vent remaining cut plasma gas upstreamthrough the torch lead and out the manifold within the plasma cuttingsystem power supply to reduce pressure in the plasma arc torch. Themethods can also further include initiating a plasma arc shut downsequence.

The venting the first conduit of the torch lead can include opening avalve within a plasma cutting system power supply to which the torchlead is attached. The selecting the cut plasma gas can transition a gassupply at the plasma arc torch from the pre-flow plasma gas of the firstconduit to the cut plasma gas of the second conduit in less than about 1second.

In some examples, a distance between the valve in the torch receptaclecan be at least about 2 meters from the manifold within the plasmacutting system power supply.

Embodiments described herein can have one or more of the followingadvantages.

The systems and components described herein can be used to carry out anyof various methods for controlling and delivering gases within a plasmacutting system. For example, the precise and dynamic control by thesystems described herein can be used to control, modify, tailor,manipulate, and optimize gas flows and/or selections within the plasmacutting system. In some embodiments, this can correspond to or match gasprofiles, pressures, and selections for given processes to improve thecut quality or to prolong electrode life by reducing plasma torchramp-down errors. A ramp-down error (RDE) can occur when the plasmasystem experiences a sudden loss of the plasma arc, for example, whenthe plasma torch runs off of the workpiece and is unable to complete thecoordinated ramp-down of plasma gas plenum pressure and cutting current(which in some cases is referred to as “Long Life Technology”). Thesudden loss of the arc without a proper arc extinguishing sequence canresult in high pressure gases blowing over molten emitter material andthus excessive wear. That is, the sudden loss of arc can cause increasedhafnium wear, especially in the presence of oxygen. For example, in somecases, without a proper arc extinguishing sequence, when the plasma arcis immediately lost, the high pressure of the plasma gas continuing toflow as if the plasma arc is still connected to the workpiece can blowaway molten emitter material, which can lead to the wear. Thus, preciseand accurate plasma gas ramping techniques can be especially useful forprolonging electrode life when the steady state cutting process istransitioned to torch shutdown (i.e., extinguishing the arc). That is,the power supply can, upon predicting/detecting an undesired arc loss isabout to occur, which could cause unnecessary wear to the electrode ifthe gas delivery is not adjusted to account for upcoming arc loss, takeaction to limit such unnecessary wear to prolong life of the electrodeby quick and responsive adjusting of plasma gas provided to the torch.

For example, the systems and methods described herein can be implementedand used in association with other torch control systems that canmonitor these electrical, system, and control parameters to predict whena plasma arc is about to be lost, for example, when the plasma torchtravels beyond the edge of a material being processed. In response, thepower supply can quickly take action to prevent sudden loss of the arc,which could result in electrode wear and a shorter lifetime. Asdiscussed below, this quick action to prevent sudden loss of the arc caninclude adjusting electrical parameters of the arc, gas flows to thetorch, or motion of the torch itself. Additional details regarding rampdown error detection and prevention can be found in Applicant's relatedco-pending U.S. patent application Ser. No. 15/287,694, filed on Oct. 6,2016 and titled “Controlling Plasma Arc Torches and Related Systems andMethods,” the contents of which are hereby incorporated by reference intheir entirety. Such controlled gas delivery methods during shut downsequences have been shown to improve consumable life, such as usableelectrode life. For example, electrode life can be hindered (e.g.,limited) by long plasma pressure ramp down times and the transition frompre-flow gas to cut flow gas.

Whereas, the systems and methods described herein can be used to improveelectrode life and torch performance by providing faster gas switchingtransition times. For example, conventional systems in which gas isswitched at the power supply can cause long gas transitions, resultingin some blend of pre-flow and cut flow gases in the lead line deliveredto the torch. This can cause an issue in that the chemistry of somegases is better suited for pre-flow, the chemistry of some other gasesis better suited for cutting, and the chemistry of some other gases canbe better suited for ramp down (e.g., during torch shut down). Thus, theability to quickly switch between these different gases in a controlledand precise manner can improve cut quality, consumable life, systemresponsiveness, and provide other benefits. Whereas, using the systemsdescribed herein, gas transition from pre-flow to cut flow can occur ator near the torch, which results in faster transition times and thuslonger electrode life. For example, some conventional systems mayrequire ramp down times of at least 250 microseconds, but some of thesystems described herein can have ramp down times that are less thanabout 50 microseconds.

Additionally, quickly changing gas delivered to the torch at a positionnear the torch, such as at the torch receptacle, can help to make torchperformance and operations be more consistent among different torchesconfigurations (e.g., torches of different lengths (e.g., differenttorch lead line lengths)). For example, some conventional systems haveonly one plasma gas line connected to the torch that is used to provideboth pre-flow and cut flow gases. Thus, the gas switching from pre flowto cut flow happens far away from the torch and the actual transition ofgases within the torch is typically dependent on (or otherwise affectedby) gas lead lengths. Whereas, the systems and methods described herein,in which gas switch can occur closer to the torch, can provide for torchcontrol and gas switching response times that are substantiallyindependent of lead length. For example, to expel a desired gas (e.g.,to expel a pre-flow gas in order to use cut flow gas or to expel cutflow gas to extinguish a torch), conventional torch systems typicallyactivate a valve (or have a vent valve) at or near the power supply(i.e., on an end of the lead line opposite the torch, in a gas meteringconsole, etc.) to change gas delivered to the torch. Once the valve isactivated, the residual gas (e.g., gas present in the lead line) istypically allowed to be expelled from this valve through the torch.However, this can cause undesired delays in the change of gas or anundesired mixing of gases. Thus, as a result of the systems and methodsdescribed herein in which the multiway valve is located close to thetorch (e.g., less than about 12 inches), gas can be switched from apre-flow gas to a cut flow gas much more quickly.

In addition to increasing the ability to switch gases for torch rampdown, the systems and methods described herein can utilize the fast gasswitching techniques during torch start-up, for example, to transitionfrom a pre-flow gas to a cut flow gas nearly instantaneously (e.g., inless than about 50 microseconds). As discussed in detail below, pre-flowgases are gases better suited for starting and prolonging electrodelife, so they are desired to be used for ignition. Then, once the arc istransferred, gas switching can happen to provide a cut flow gas, whichis better suited for cutting. In some conventional systems, this switchhappens at arc transfer but there is a considerable delay in start ofcut to account, in part, for the delay in gas switching (e.g., for thepre-flow gas to decay out of the lead line and be replaced by the cutflow gas). Whereas, using the systems and methods described herein thathave faster and better controlled gas switching, cutting can begin morequickly and or instantly/immediately following arc transfer.

Additionally, this gas changing sequence in conventional systems at ornear the power supply can cause inconsistent performance between torcheshaving different lead line lengths. That is, conventional plasma cuttingplatforms offer different lead/hose lengths (e.g., between the meteringconsole (e.g., at the power supply) and the torch) in order to cater tocustomer specific requirements. This length variation, which can varybetween about 6 feet to about 50 feet (or more), can result ininconsistent gas transition times and profiles which compromise qualityand consistency, and/or in gas ramp time variation making consumablelife partly dependent on system configuration and can deprive customersof uniform consumable performance. This means that overall life of theelectrode can be hindered by long plasma pressure ramp down times, whichcan drive/require these times via the distance between the controlelements (e.g., gas control valves) and the torch. Furthermore,electrode life can also be effected by the transition from pre-flow gasto cut flow gas and the timing of this transition needs to becontrolled. For example, in some conventional plasma systems, unwantedgases from within the lead are expelled from the torch itself, longerlead lengths will typically require a longer time to evacuate all of theresidual gas than a shorter lead length will. Whereas, in some examples,instead of having to extinguish a plasma arc and then drain the gas inthe lead line, the systems herein can be used to drain the gas supplyline while the arc is still on. For example, the inconsistencies can bereduced by adding the gas switching valve (e.g., a three way valve)immediately upstream of the torch and connecting two plasma lines(pre-flow and cut-flow) to this valve. Thus, gas switching andpredictable ramp downs can be achieved independent of lead length.Bringing two plasma lines close to the torch can help to provide fast(e.g., near instantaneous) switching of gases (pre-flow to cut-flow) andimproved ramp down responsiveness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a plasma arc torch system having asystem for back-venting in a plasma arc torch upstream through a plasmatorch lead line.

FIG. 2 is a schematic diagram of a plasma arc torch system having asystem for back-venting in a plasma arc torch upstream through a valveat or near the torch.

FIG. 3 is a side cutaway view of an example torch having a multiwayvalve disposed therein for selectively providing gas to a plenum area.

DETAILED DESCRIPTION

In some aspects, as discussed herein, the systems and methods describedherein can include a plasma cutting system having one or more preciselyand dynamically monitored and controlled gas parameters, such as plasmagas flow or shield gas flow. The precise control of these systems hasbeen found to be useful to implement several advantageous torch controlmethods described herein. Example methods, as discussed in detailherein, include quickly adjusting flow of different plasma gasesprovided to the torch during plasma arc start-up or ramp-downprocedures. More responsive gas handling has been found to yield betterand/or more consistent consumable performance and life.

Referring to FIG. 1, in some cases, a plasma cutting system (e.g.,plasma arc torch system) 50 for back-venting plasma gas in a plasma arctorch upstream through a plasma torch lead line can include a plasmatorch power supply 100, a plasma torch lead line 120, a torch receptacle140, and a plasma arc torch 150 having a torch body 160. The torchreceptacle 140 can serve as an interfacing component between the leadline 120 and the plasma arc torch 150.

The power supply 100 can include a metering console with a set of gassupplies, which can include a shield gas supply 102, a first processinggas (e.g., plasma gas (e.g., a pre-flow plasma gas)) supply 104, and asecond processing gas (e.g., plasma gas (e.g., a cut flow plasma gas))supply 106. The configurations of the different gas supplies can varybased on the desired material processing operation. For example, in somecases, the first plasma gas 104 can include nitrogen. In some cases, thesecond plasma gas 106 can be oxygen. The gas supplies can includevarious hardware components, such as valves (e.g., three-way valves orproportional valves) and pressure transducers, which can be used tocontrol and monitor the flow of gas.

The power supply 100 also typically includes a torch lead manifold 108.The torch lead manifold 108 can be used to selectively fluidly connectthe set of gas supplies to the torch body 160, for example, via theplasma torch lead line 120. The torch lead manifold 108 can include apneumatic switch that can open and close different flow paths to permitor limit gases from flowing to and from torch lead line 120.

The power supply 100 can also include a vent (e.g., a vent valve) 110 toreduce the pressure of one or more of the gases. For example, the vent110 can permit a gas to be opened to atmospheric pressure. In somecases, the vent valve 110 can be fluidly connected to the firstprocessing gas supply 104 and be configured to vent the first processinggas (e.g., from the torch lead line, as discussed below) to theatmosphere. In some cases, as detailed below, this venting can beperformed to quickly evacuate processing gas (e.g., upstream) from thelead line 120, while the torch 150 (e.g., plenum) may be exhausteddownstream/forward through the torch tip.

The plasma torch lead line 120 is configured to connect the plasma torch150 to the power supply 102. For example, the lead line 120 can beconfigured to connect to the power supply 102 to couple to a torch leadmanifold 108 and the torch receptacle 140. Torch lead manifold 108 maybe located external/separate to power supply 102 or within power supply102. The plasma torch lead line 120 is typically configured to deliverfluids (e.g., torch gases) to the torch 150. For example, the lead line120 can define a set of fluid passages (e.g., conduits) to convey thefirst plasma gas and the second plasma gas from the plasma torch powersupply to the torch body 160. The lead line 120 can include a shield gaspassage 122, a first processing gas passage 124, and a second processinggas passage 126. The shield gas passage 122 can convey the shield gas tothe torch 150 (e.g., to the torch receptacle 140). The first processinggas passage 124 can convey the first processing gas to the torch 150(e.g., to the torch receptacle 140). The second processing gas passage126 can convey the second processing gas to the torch 150 (e.g., to thetorch receptacle 140). The lead line can include any of variousstructurally suitable components to convey the gases. For example, thelead line 120 can include a multi-chamber hose, such as a hose havingtwo or more (e.g., three to accommodate the shield gas, first processinggas, and second processing gas) separated flow paths. In some cases, thelead line 120 can include three distinct hoses coupled to one another.

The plasma torch lead line 120 can have any of various lengths dependingon the desired operation and environment of use. For example, in somecase, the plasma torch lead line 120 can have a length 121 that is atleast about 2 meters, 5 meters, or 50 meters.

The torch receptacle 140 can be configured to couple a plasma arc torchbody 160 to the plasma torch power supply 100, for example, by the leadline 120. The torch receptacle 140 can include a body 142 having a firstend 143 to couple to the plasma torch lead line 120 and a second end 144shaped to connect to a torch body 160 of the plasma arc torch 150. Thereceptacle 140 can include a set of ports 145 defined within the firstend 143 of the body 142. The ports 145 can be configured to fluidlyconnect to the set of fluid passages 122, 124, 126 of the plasma torchlead line 120. The set of ports 145 typically comprises a first plasmagas port 145A and a second plasma gas port 145B. The first plasma gasport 145A can be configured to receive a plasma pre-flow gas (e.g., gas104) and the second plasma gas port 145B can be configured to receive aplasma cut flow gas (e.g., gas 106). A third port 145C can be a shieldgas port configured to receive a shield gas (e.g., gas 106).

The body 142 can define a set of fluid flow paths (e.g., gas channels)148 disposed substantially within the body to fluidly couple to thefluid conduits 122, 124, 126 within the torch lead 120 via the gas ports145A, 145B, 145C. For example, the body can define a first plasma gaschannel 148A connected to the gas port 145A, a second plasma gas channel148B connected to the gas port 145B, and a shield gas channel (e.g.,shield gas conduit) 148C connected to the gas port 145C. As discussedbelow, the first plasma gas channel 148A and the second plasma gaschannel 148B can fluidly connect gas ports 145A and 145B to a valve 146to select between the two gases flowing therein. For example, the valve146 can select between the two gases flowing in the first plasma gaschannel 148A and the second plasma gas channel 148B, respectively, anddetermine which gas can flow on to the torch (e.g., via a torch gasconduit 149 discussed below). That is, the valve 146 can block one ofthe gases (e.g., either the gas in the first plasma gas channel 148A orthe gas in the second gas channel 148B) from flowing on to the torchwhile permitting the other gas to flow on to the torch. The shield gasport 145C can be fluidly connected to a shield gas conduit 148C formedbetween the first end 143 and the second end 144.

The body 142 can be formed of any of various materials. In someembodiments, the body 142 is formed of a substantially insulativematerial. For example, the body can be made of Ryton/Thermec, Techtron,Torlon, Vespel, or other material.

The body 142 has a short length (e.g., shorter relative to othercomponents such as the lead line 120). As discussed below, componentswithin the receptacle (e.g., valves) can be used to quickly evacuategases from the torch body 160 so that one or more material processingsequences, such as a torch shut down sequence (e.g., a ramp down errorsequence), which may perform more optimally in the presence or absenceof certain gases, can be initiated. For example, in some embodiments,the body can have a length that is less than about 1 foot (e.g., lessthan about 6 inches) between the first end 143 and the second end 144.

The receptacle 140 can also include a fluid selection valve (e.g., a3-way multiway valve) 146 disposed within the body 142 and fluidlyconnected to the set of ports 145, to be fluidly coupled to the firstpassage 124 and to the second passage 126 in the plasma torch lead line120. The valve 146 is configured to fluidly connect the first and/orsecond passage to a torch gas conduit 149 formed at or near the secondend 144. The torch gas conduit 149 can deliver the gas selected by thevalve 146 to the torch body 160. In some cases, the torch gas conduit149 is fluidly connected to the torch tip, for example, withoutobstructions between the valve 146 and the plasma plenum. In someembodiments, the torch gas conduit 149 of the body has a volume of lessthan about 0.3 cubic inches (e.g., between the valve 146 and the torchtip (e.g., between the valve 146 and the outer surface of the downstreamsecond end of the receptacle body)). In some embodiments, the torch gasconduit 149 has a volume of less than about 0.2 cubic inches. Forexample, in some cases, the torch gas conduit volume can be a defined orenclosed space between the valve 146 and an output port 147 of thereceptacle (e.g., formed along an outer surface of second end of thebody) that provides the selected processing gas to the torch. This smallvolume of the torch gas conduit 149 can help to provide fast gastransition times and reduce (e.g., minimize, eliminate) gas pressuredecay and the associated negative effects of prolonged gas pressuredecay, such as prolonged ramp down times. Additionally, thesubstantially fixed volume of the torch gas conduit 149 can provideconsistent behavior in timing of gas transitions from pre-flow to cutflow gas during torch ignition and a consistent ratio between the gaspressure and current during extinction of the arc.

In some embodiments, the 3-way valve 146 is configured to select gasfrom either the first passage (e.g., conduit) 124 or the second passage(e.g., conduit) 126, for example, as it enters the ports 145A and/or145B, and permit delivery of the selected gas to the torch body via thetorch gas conduit 149. For example, the 3-way multiway valve 146 can beconfigured to change (e.g., selectively manipulate) a flow of fluidsbetween the first end 143 and the second end 144 of the body to selectfrom primary gases that have entered the set of ports 145 and are beingconveyed to torch gas conduit 149. For example, the valve 146 can beused to fluidly connect to the first processing gas 104 and the secondprocessing gas 106 to the torch gas conduit 149. The valve 146 can alsoselectively deliver a selected primary gas (e.g., from the first passage124 or the second passage 126) to the torch through the torch gasconduit 149.

In addition to delivering gas to the torch, the valve 146 can fluidlyconnect the torch gas conduit 149 to a location upstream of the torch,such as the power supply (e.g., to the torch lead manifold 108). Thisfluid connection to a component upstream can be used to permit ventingthrough the torch lead manifold 108 to atmospheric pressure. Forexample, the torch lead line 120 can fluidly couple at least one of thegas channels 148 to vented atmospheric pressure. For example, gaspresent in one or more of the fluid passages 122, 124, 126 of the leadline 120 can be expelled from the torch system through the torch leadmanifold 108 and then out of the system (e.g., to atmosphere) throughthe vent valve 110 (e.g., rather than all being exhausted forwardthrough torch tip). Additionally, in some embodiments, the valve 146 canbe used to limit the flow of gas (e.g., one of the plasma gases (e.g.,pre-flow or cut flow) from entering the torch gas conduit 149 andtherefore also the torch body 160. In some cases, an excess of plasmagas blocked from entering the torch gas conduit 149 by the multiwayvalve 146 can be vented upstream through the torch lead 120.

The multiway valve 146 can include any of various types of suitable gasswitching valves. The multiway valve 146 can be configured such that atleast one of the processing gases (e.g., the pre-flow gas or the cutflow gas) is always fluidly connected to the torch gas conduit 149. Forexample, the multiway valve 146 can be quickly switched back and forthso that at least one of the gases always flows to the torch.

As mentioned above, the receptacle 140 can be positioned at or near thetorch body 160 in order to quickly and efficiently alter or replace gas(e.g., plasma gas) within the torch. In some embodiments, the multiwayvalve 146 can be located at a length 141 that is less than about 12inches (e.g., less than about 6 inches) from a plasma plenum 162 of theplasma arc torch body 160. In some embodiments, the valve 146 within thereceptacle can be positioned away from the power supply 100. Forexample, the valve 146 in the torch receptacle 140 can be at least about2 meters from the manifold 108 of the plasma cutting system power supply100.

The plasma cutting systems depicted and described with respect to FIG. 1can be implemented in various examples, such as mechanized torches orhandheld portable torches. For example, referring to the cutaway view ofFIG. 3, a mechanized torch 350 can include a valve 346 to direct one ormore processing gases therein received from a power supply, such as thepower supply 100 described above. The torch 350 can include a receptacle340 configured to couple to a torch body 360. The receptacle can defineports 345A and 345B, connected to processing gas channels 348A and 348B,and permit delivery of the selected gas to the torch body 360 via atorch gas conduit 349. A multiway valve 346, as described above andbelow, can be disposed within the receptacle 340 to selectively permitgases entering the receptacle through the ports 345A, 345B andprocessing gas channels 348A, 348B to proceed and flow on to a plasmaplenum of the torch.

In some aspects, the plasma cutting systems described above (e.g.,plasma arc torch system 50) can be used to select between a set ofplasma gases (e.g., a pre-flow gas and a cut flow gas) in a torchreceptacle (e.g., the receptacle 140) that couples a plasma arc torch(e.g., the torch 150) to a torch lead (e.g., the torch lead line 120),where the torch receptacle 140 includes a valve (e.g., multiway valve146) configured to manipulate a flow of fluids to the plasma arc torchbetween the gases of the set of plasma gases (e.g., by selecting betweenthe pre-flow gas and the cut flow gas).

In some embodiments, an example method can include supplying a pre-flowplasma gas (e.g., from gas 104) through a first conduit (e.g., the firstprocessing gas passage 124) of the torch lead coupled to the torchreceptacle, the pre-flow plasma gas traveling to the plasma arc torchthrough the valve (e.g., valve 146). This can allow pre-flow gas, suchas nitrogen to flow to the torch (e.g., to the plasma plenum of thetorch).

In some cases, the method can include igniting a plasma arc within theplasma arc torch in the presence of the pre-flow plasma gas. The torchsystem can detect or sense that ignition has occurred and a plasma archas been formed between the electrode and the nozzle of the torch.

With the plasma arc ignited, the method can include selecting a cutplasma gas (e.g., from gas 106). For example, the cut plasma gas can beselected by activating the valve to limit further flow of the pre-flowplasma gas downstream to the plasma arc torch. Activating the valve canalso permit flow of the cut plasma gas from a second conduit (e.g., thesecond processing gas passage 126) of the torch lead to the plasma arctorch through the valve. Switching from the pre-flow gas to the cut flowgas can happen quickly. Since the receptacle 140 is located close to thetorch, the change in gas provided to the torch can be accomplishedquickly, for example, typically faster than if the change in gas flowwas directed at the power supply (e.g., only at the manifold 108). Thisis typically because if the gas is switched at or near the torch, thecontents of the lead line need not be exhausted from the lead line andthrough the torch before the gas change can be completed. As discussedherein, such fast responsiveness in gas flow can be useful in enactingchanges to a material processing operation, such as an accelerated shutdown procedure. Some testing has shown that gas ramp down time can bereduced using the systems and methods described herein by about 35milliseconds to about 100 milliseconds. For example, the selecting thecut plasma gas can transition a gas supply (e.g., from the torch gasconduit 149) at the plasma arc torch from the pre-flow plasma gas of thefirst conduit to the cut plasma gas of the second conduit in less thanabout 1 second.

In some embodiments, the method can include venting the first conduit ofthe torch lead to a pressure lower than that of the plasma plenum, suchas atmospheric pressure, at a position upstream of the plasma arc torch,which can release the pre-flow plasma gas from the torch lead. In somecases, venting the first conduit of the torch lead can include opening avalve within a plasma cutting system power supply to which the torchlead is attached. For example, the manifold 108 within the power supplycan be opened to vent the first processing gas passage 124 toatmospheric pressure. In some cases, this can be performed after thevalve blocks flow of the pre-flow gas and permits the cut flow gas toflow to the torch.

The method can also include performing a plasma cutting operation usingthe cut plasma gas. For example, once the plasma gas has been switched,for example using the valve 146, from the pre-flow to cut flow, thetorch can carry out a cutting operation using the cut flow gas as plasmagas.

In some embodiments, the methods can also include activating the valve(e.g., valve 146) in order to limit further flow of the cut plasma gas(e.g., gas 106) from passing downstream to the plasma arc torch from thesecond conduit (e.g., the second processing gas passage 126). Activatingthe valve (e.g., valve 146) can also vent the remaining cut plasma gasupstream through the torch lead and out the manifold (e.g., manifold108) within the plasma cutting system power supply to reduce pressure inthe plasma arc torch. That is, the valve can be switched to block cutgas from further traveling to the torch while the manifold 108 can beopened so that any cut gas present in the lead line can be expelled fromthe system. In some embodiments, this can be performed in conjunctionwith a plasma arc shut down sequence. In some cases, the method caninclude activating the valve just prior to, or simultaneously with,initiating a plasma arc shut down sequence.

Other configurations are possible. Unless otherwise stated, the otherexample embodiments can include one or more features or components fromthe examples described above. For example, in some embodiments, thevalve 146 can be connected directly to a vent. For example, gases may bechanged or controlled at the power supply and provided to the receptacle140, such as via the port 145A and the port 145B can be vented, forexample, to atmospheric pressure. One or more of the gas deliverymethods described herein can be carried out using such a configurationby venting at the receptacle rather than at the power supply.

In some embodiments, a plasma cutting system can be configured to havemultiple gas flow directing valves at or near the torch. For example,referring to FIG. 2, a plasma cutting system can include a power supply200 having a metering console that provides a set of gas supplies, whichcan include a shield gas supply 202, a first processing gas (e.g.,plasma gas (e.g., a pre-flow plasma gas)) 204, and a second processinggas (e.g., plasma gas (e.g., a cut flow plasma gas)) 206. Theconfigurations of the different gas supplies can vary based on thedesired material processing operation.

Similar to the examples described above with respect to FIG. 1, theplasma cutting system can include a lead line 220 that includes a shieldgas passage 222, a first processing gas passage 224, and a secondprocessing gas passage 226.

The valves to control gas can be disposed in or on a torch 150 or withinanother structural component, such as a torch receptacle 240. In someembodiments, a multiway valve (e.g., a 3-way valve) 246 can be disposedon or near the torch body 160 to selectively deliver the desiredprocessing gas to the torch, as described above. Additionally, anothervalve 247 can be disposed at or near the torch, such as between themultiway valve 246 and the torch body 160 to permit or block theselected processing gas from passing on to the torch. As illustrated,the valve 247 can also be fluidly connected to a vent 210. During use,the valve 247 can therefore be used during transition periods, start-up,or shut down sequences in order to quickly vent processing gas upstreamof the torch. That is, pursuant to one or more of the methods describedherein, valve 247 can improve an accelerated shut down sequence bysignificantly reducing the vent time/gas pressure decay and evacuationof gases in the plasma plenum of torch 150.

While various embodiments have been described herein, it should beunderstood that they have been presented and described by way of exampleonly, and do not limit the claims presented herewith to any particularconfigurations or structural components. Thus, the breadth and scope ofa preferred embodiment should not be limited by any of theabove-described exemplary structures or embodiments, but should bedefined only in accordance with the following claims and theirequivalents.

What is claimed:
 1. A torch receptacle for coupling a plasma arc torchto a torch lead of a plasma cutting system, the torch receptaclecomprising: a body having a first end shaped to connect to the torchlead and a second end shaped to connect to a torch body or a torch tipof the plasma arc torch; a pair of entry ports disposed at the first endof the body and configured to fluidly connect to a set of fluid conduitsdisposed within the torch lead; and a multiway valve having at least twoinlets and an outlet disposed within the body and fluidly connected tothe pair of entry ports at the first end of the body and to a torch gasconduit disposed at the second end of the body, the multiway valve beingconfigured to select between a first plasma gas and a second plasma gasentering the pair of entry ports by selectively blocking a flow ofeither the first plasma gas or the second plasma gas entering the body,thereby delivering a selected plasma gas through the torch body to thetorch gas conduit to supply the plasma arc torch.
 2. The torchreceptacle of claim 1 wherein the body is formed of a substantiallyinsulative material.
 3. The torch receptacle of claim 1 wherein the bodyhas a length of less than about 1 foot between the first end and thesecond end.
 4. The torch receptacle of claim 1 wherein the multiwayvalve is a three-way valve fluidly coupled to a first conduit of the setof fluid conduits, a second conduit of the set of fluid conduits, andthe torch gas conduit and is configured to select gas from either thefirst conduit or the second conduit and permit delivery of the selectedgas to the torch body via the torch gas conduit.
 5. The torch receptacleof claim 1 wherein the body defines a set of fluid flow paths disposedsubstantially within the body to fluidly couple the multiway valve tothe fluid conduits within the torch lead.
 6. The torch receptacle ofclaim 1 wherein the multiway valve is located less than 12 inches from aplasma plenum of the plasma arc torch.
 7. The torch receptacle of claim1 wherein the pair of entry ports comprises a first plasma gas entryport and a second plasma gas entry port, the first plasma gas port beingconfigured to receive a plasma pre-flow gas and the second plasma gasport being configured to receive a plasma cut flow gas.
 8. The torchreceptacle of claim 1 wherein the torch gas conduit has a volume of lessthan about 0.3 cubic inches.
 9. The torch receptacle of claim 8 whereinthe torch gas conduit has a volume of less than about 0.2 cubic inches.10. The torch receptacle of claim 1 wherein the torch lead fluidlycouples at least one of the set of conduits to vented atmosphericpressure.
 11. The torch receptacle of claim 10 wherein an excess ofplasma gas blocked from entering the torch gas conduit by the multiwayvalve is vented upstream through the torch lead.
 12. The torchreceptacle of claim 1 wherein the multiway valve is configured to switcha supply of gas provided to the torch body via the torch gas conduitbetween gases entering the pair of entry ports.
 13. The torch receptacleof claim 1 comprising a shield gas port fluidly connected to a shieldgas conduit formed between the first end of the body and the second endof the body.
 14. A plasma arc torch system comprising: a plasma torchpower supply comprising: a set of gas supplies comprising a first plasmagas and a second plasma gas; a torch lead manifold to fluidly connectthe set of gas supplies to the plasma torch lead line; and a vent valveto vent at least one of the first plasma gas and the second plasma gasto atmospheric pressure; a plasma torch lead line configured to coupleto the torch lead manifold, the plasma torch lead line defining a set offluid passages to convey the first plasma gas and the second plasma gasfrom the plasma torch power supply; and a torch receptacle for couplinga plasma arc torch to the plasma torch power supply, the torchreceptacle comprising: a body having a first end to couple to the plasmatorch lead line and a second end shaped to connect to a torch body or atorch tip of the plasma arc torch; a pair of entry ports defined at thefirst end of the body and configured to fluidly connect to the set offluid passages of the plasma torch lead line; and a multiway valvehaving at least two inlets and an outlet disposed within the body andfluidly connected to the pair of entry ports at the first end of thebody, to be fluidly coupled to a first passage of the set of fluidpassages in the plasma torch lead line and to a second passage of theset of fluid passages in the plasma torch lead line, and to a torch gasconduit formed in the second end of the body having a volume of lessthan about 0.3 cubic inches, the multiway valve being configured toselect between a first plasma gas and a second plasma gas entering thepair of entry ports by selectively blocking a flow of either the firstplasma gas or the second plasma gas entering the body, therebydelivering a selected plasma gas from either the first passage or thesecond passage through the torch body to the torch gas conduit to supplythe plasma arc torch.
 15. The torch receptacle of claim 1 wherein themultiway valve is configured to transition between a first plasma gasand a second plasma gas in less than about 1 second.
 16. The plasma arctorch system of claim 14 wherein the multiway valve is configured totransition between a first plasma gas and a second plasma gas in lessthan about 1 second.
 17. The plasma arc torch system of claim 14 whereinthe multiway valve is located less than 12 inches from a plasma plenumof the plasma arc torch.